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Avalanche Forecast

Archived

Jan 27th, 2023–Jan 28th, 2023

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Cariboos, North Rockies, Blue River, Clearwater, McBride, Premier, Quesnel, Sugarbowl, Clemina, North Monashee, McGregor, Renshaw, Robson.

High consequence persistent and deep persistent slab avalanches have been reported every day over the past week. Stick to low angle terrain away from any overhead hazard.

Read more in our latest forecaster blog.

Confidence

Low

Avalanche Summary

On Thursday a few very large (size 2.5-3) natural wind slab avalanches were reported around 1800-2000 m. Additional ongoing evidence of weak basal facets continued with a size 3 deep persistent avalanche reported on a steep southeast slope at 2400 m.

Both natural and human-triggered persistent and deep persistent slab avalanches continue to be reported daily. Last Wednesday there was a report of a remotely triggered (from a distance) size 2 persistent slab avalanche at treeline on a south aspect. There was also a size 3 naturally triggered deep persistent slab avalanche with a wide propagation reported on a south aspect in the alpine.

On Monday, a fatal skier-triggered avalanche incident occurred in the Selkirks near Revelstoke. The avalanche was on an east aspect at 1900 m. It occurred on a steep, unsupported open slope below treeline and failed on a weak layer of surface hoar buried in early January. This large avalanche (size 2) had a crown depth of 50 cm.

Last weekend (Saturday), a fatal avalanche Incident occurred in the Oasis riding area south of Valemont. This avalanche resulted in a rider fatality. This was a remotely triggered (from a distance) size 2.5 deep persistent slab avalanche on a north-northwest aspect at 2100 m. More details can be found here.

Avalanches like these are most likely to be triggered on steep, shallow and previously undisturbed slopes. Your best defence at this time is to stay diligent in choosing low-consequence terrain that has been heavily trafficked throughout the winter. Stay disciplined and adjust your expectation for this winter.

Snowpack Summary

Surface snow varies by elevation, with recent warm temperatures turning snow moist around treeline elevations and now heading into a cooling trend. West and north winds will continue to affect exposed terrain and form wind slabs near ridgetops. 20-60 cm of recent snowfall sits above a layer of surface hoar as well as a sun crust on steep solar aspects.

A prominent layer of buried surface hoar can be found roughly 50-90 cm deep. It is found in some places but not in others, and has been recently reactive to human triggering. The bottom of the snowpack is made up of large weak facets buried in late November, causing the Deep Persistent Slab problem for this region.

Weather Summary

Friday night

Isolated flurries, 5 cm. Ridge wind northeast 15-30 km/hr. Alpine temperature -16 C. Artic air bringing cold temperatures and northerly outflow winds.

Saturday

Increasingly Sunny. Ridge wind northeast 15-30 km/hr. Alpine temperature -20 C.

Sunday

Sunny. Ridge wind northeast 20-30 km/hr. Alpine temperature -23 C.

Monday

Sunny. Ridge wind northeast 5-15 km/hr. Alpine temperature -25 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • Approach lee and cross-loaded slopes with caution.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.